Writing instrument



Jan. 19, 1954 E. w. RICKMEYER 2,666,416

WRITING INSTRUMENT Filed Sept. 11, 1948 INVENTOR.

Patented Jan. 19, 1954 WRITING INSTRUMENT Ernst W. Rickmeyer, Prospect Heights, Ill., assignor to The Parker Pen Company, Janesville, Wis., a corporation of Wisconsin Application September 11, 1948, Serial N o. 48,837

This invention relates to ink-Writing instruments and has to do particularly with a capillary writing point and ink feed means therefor.

An object of this invention is to provide an improved writing instrument.

Another object is to provide aA writing instrument of the stylus point type having improved means for feeding ink to the writing point and for admitting air thereinto to insure a controlled and even feed of ink to the writing point.

Another 'object is to provide a writing` instrument of the stylus point type capable of use with a relatively thick, pasty ink.

Another object is to provide a writing instrument of the stylus point type having an improved writing point formed from porous sintered metal.

Another object is to provide an improved writing element or point for a writing instrument of the stylus point type.

Another object is to provide an improved ink feed element for a writing instrument of the stylus point type. f

A further object is to provide an` improved ink cartridge for a writing instrument.

Another object-is to provide-.a writing instrument having-an improved venting arrangement.

Another object is to provide a Writing instrument having a porous metal Writing point which does not starve or nood when used in writing and which does not leak during periods of non- Writing. l v

Other'objects and advantages of the invention will appearjfrom the following description taken in connection with the appended drawing, wherein; f l

`Figure 1, is a longitudinal sectional view of a preferred embodiment of my invention;

3 Claims. (Cl. 1Z0-51) Fig.2 is an enlarged, transverse, sectional view taken along line 2--2 of Fig. 1";

Y Fig. 3 is an enlarged, transverse, sectional View taken along line 3-3 of Fig. 1; and

Fig. 4 is an enlarged, transverse, sectionalview taken along line 4 4 of Fig. 1.

In accordance. with my invention, a ywriting instrument is provided which is adapted foruse With .a relatively .thick, somewhat viscous ink such as commonly employed in ball point Writing instruments. The Writing instrument of the present invention has fa writing point or element Y formed from porous sintered material, the pores being of capillary size and serving to retain ink therein by capillary actionexcept when the writing element is in contact with a writing surface. The writing element is formed as a hollow member having a closed forwardv end, thereby permitting air to :enterinto` the interior of the member to prevent locking of the ink ow andto permit ink to be Withdrawn readily from the member in writing.

Referring now particularly to Fig. l, the writing instrument includes a barrel or casing which preferably is formed by a forward barrel section l0 anda rear barrel section or end cap H` detachably connected as bya threaded sleeve l2. While the barrel may be formed of barrel sections of nearly equal size,` or with a long rear barrel section and short forward barrel section, I prefer to employ a construction such as that illustrated. The barrel defines a chamber I3 having an opening i4 at its forward end through which projects a writing element 25 hereinafter described more in detail.

The writing element 25 is disposed-in the forward end of the casing l0 and takes the form of a hollow member formed of porous sintered metal. The writing element preferably is of generally tapered conical form, providing a principal body portion of substantial diameter and a forward tip portion of reduced size adapted to serve as a writing point and Which is capable of depositing on a writing surface on ink line of the desired width. The porous sintered metal from Y suiciently large to permit ink to be withdrawn therefrom by capillary action when the Writing element is placed in Writing contact with a writing surface. retain the ink by capillary action so that ink will not leak therefrom during periods of non-use of the instrument. I have found that satisfactory results may be obtained by forming the pores so that they have a Wal1-to-wal1 dimension of from around 0.006 to around 0.008" or somewhat larger. It Will be understood that the `hollow writing element is formedto the desired shape by molding in a suitable mold the material or materials from which the sintered metal is formed by the sintering operation, as more fully described in my aforesaid copending application.

Ink is delivered to the Writing element 25 from the reservoir, hereinafter described more in detail, by an ink feed element 27 which preferably4 The pores are sufficiently ne to I is formed of porous sintered material in a manner generally similar to the writing element. The feed element 21 is formed with an enlarged head portion 28 adapted to seat snugly in the forward portion of the barrel, a small, rearwardly facing shoulder 29 preferably being provided to serve as an abutment to aid in positioning the feed element in the barrel. The head 28 preferably is formed with such diameter that it is held frictionally against rearward displacement when not otherwise securely held in the barrel. The feed element 21 has a body portion 30 extending forwardly from the head 28 and shaped to fit tightly within the open rear end of the writing element 25, with the periphery of the body portion 3Q in rm abutment with the corresponding interior of the surface of the writing element 25 to securely retain the writing element 25 frictionally on the feed element 21. At the same time, the abutting surfaces of the feed element 21 and writing ele- Vment 25 are in sufficiently intimateV contact to place the pores of these two elements in ink feeding relation to provide for the transfer of ink from the feed element to the writing element. It will be noted that in the embodiment illustrated herein the forward face of the head 28 is in abutment with the rearward face of the writing element 25 and thus an additional connection is provided between the pores of the two elements.

The feed element 21 is formed in its rear face with a recess 3l, preferably of circular shape and adapted to snugly receive the head portion 32 ofV a "channel element 33 formed with a tubular stem 4| having a bore 35 extending therethrough and in alignment with a bore 38 extending axially through the body 30 of the feed element 21. The .stem 4l is adapted to enter the ink reservoir to place the passage .35 in feeding com- V munication therewith, thus providing a feed passage or channel leading from the interior of the reservoir to the body portion of the feedY element 30.

While the ink reservoir may be defined in. various ways, I prefer to provide an ink cartridge which isY removable from the barrel and which is adapted to be-lled with ink by the manufacturer and dispensed as va filled cartridge which may be inserted in the writing instrumentby theuser.` To this end, the cartridge is so formed as to prevent ink from leaking therefrom when the cartridge is stored or shipped but is adapted to be placed in condition for use by merely inserting it in the barrel of the writing instrument. The cartridge l preferably includes a tubular casing l5 closed at its forward end by an imperforate, puncturable closure member l1 formed of'rubber'orequivalent material and suitably secured in the forward end of the casing I'B in such manner as to v4prevent leakage of ink therefrom so long as the closure member l1 remains imperforate. To this end the forward end closure preferably is adhesively secured in the casing I6.

yll)

The rear `end of the casing I6 preferably is closed by a closure member I8 adapted to prevent ink from leaking from the casing but at thev same time adapted to permit air lto enter the casing to.v replace ink which is withdrawn from the casing IB in writing. Preferably, the rearr end 'closure IB is formed of'porous Vsintered .metal having pores of such size as to, permit air Vto pass; therethrough but sufficiently fine to prevent init from leaking from the rear end of the cartridge. The rear end closure i8 is suitably secured in the rear end of the casingA I6, a shoulder i9 being provided:

for aiding in positioning the rear end closure.

The interior of the casing I6 is vented through the rear end closure I8 and, when the cartridge is in position in the barrel IG, the reservoir is vented to the'exterior of the pen through a vent slot 2i formed in the metal sleeve l2 and a port 22 suitably located, as, for example, at the juncture of the barrel l@ and rear end cap I l. In order to insure the desired venting action, a seating element 23 is provided which takes the form of a disc of material similar to the rear end closure I8. Thedisc 23 is snugly seated in the rear end cap l I in position to be abutted by the rear end closure I3 when the cartridge l5 is assembled in the barrel l0 and the rear end cap i i is in position. rIihus, the pores in the seating disc 23 provide vent passages connecting the pores in the end closure i8 with the interior space in the end capV l l.

The ink cartridge is adapted to be inserted in the barrel l from the rear end and forced home against the rear face of the feed element 21 and the rear face of the head 32. When it is thus forced home the sharpened or barbed end 34 punctures the forward closure member ll and enters the reservoir to place the rear end of the feed passage 55 in communication with the interior of the reservoir. Ink therefore flows through the passages 35 and 36 and is drawn fronrthe latter by capillary action into the feed element 21, particularly at the body portion thereof. Ink, in turn, is drawn from the feed element 21 by capillary action into the writing element 25 and stands at the outer surface thereof. Preferably the writing element 25 is formed of porcs of slightly smaller size than the pores of the feed element 21 to insure that ink'will be drawn into the former so as to maintain ink in the same, so that the instrument is in condition for instant writing.

In writing, when the forward end of the writing element is placed in contact with a writing surface, the capillary thus established draws inl; from the writing element, and ink te replace the withdrawn ink is drawn into the writing element from the feed element'. Air to replace ink which is withdrawn from the reservoir enters the writing instrument through the port 22, the vent slot 2l, the pores in the disc 23 and the pores in the inner end closure i8.

During periods of non-use, when the pen is not employed in writing, ink is retained in the reservoir by adhesion to the walls of the casing It and by the internal cohesions of the ink, as well as by the restriction imposed by the outlet passage 35. However, the gravitational force on the ink in the reservoir, aided by the capillary effect of the outlet passage 35, is'sufcient to cause the ink torflow into the outlet passages 35 and 35, and the capillary attraction exerted by the pores of the feed element 21 causes ink to be drawn from the reservoir and into the feed element, from whence it is drawn into the writing element to replace ink withdrawn in writing. It has been found that where a porous capillary member of substantialiwall thickness is employed, locking of the ink columns may occur, dueto the inability of. air to enter the pores behind the Vink, thus causing an uneven withdrawal of ink, or even complete stoppage of the passage of ink, especially when the writingA instrument is employed in rapid writing. In order to permit ink to' pass readily along the spaces-or pores in vthe feed element 21 and the writing element 25v to replace inkl withdrawn from the latter in writing,l the writing element, and preferably also the feed vatmospheric pressure.

j spaced slightly from the adjacent wall of the f barrel to provide a space 40 into which air may formed with very thick wall portions.

The writing element therefore is formed Vas a hollow member and is provided with a space 38 therein forwardly of the feed element, which space under normal conditions contains air at The writing element is enter to maintain the outer surface of the writing velement at atmospheric pressure substantially over its entire area.v In addition, the body portion 30 of the feed element preferably is kprof vided with grooves 31 into which air may enter from the space 38 to further aid in the venting action.

Since air at atmospheric pressure is in contact with the outer face of the writing element, and also normally in contact with the inner face thereof, the ink in the pores of the writing Velement normally is under atmospheric pressure and therefore flows evenly along the `.channel provided by the pores as ink is withdrawn from the tip of the writing element. However, since air will enter empty pores more readily than ink, some air may be drawn into the po-res as the ink is withdrawn, some of this air being drawn in from the outside of the writing element and some from the space 38. Air will normally find its way through the wall of the writing element at some point and thus maintain atmospheric pressure within the space 38.

Should ink tend to flow from the reservoir to the feed element and thence to the writing element at a more rapid rate than it is withdrawn from the writing element in writing, it will tend to fsweat from the external surface of the writing element and will enter the space 4i). This space, however, is of suiciently small size to retain the ink therein and prevent it from leaking through the forward opening I4 in the barrel. When ink standsin the space 40, at least a portion ef the external surface of the feed element is sealed against the entrance of air, thus restricting the venting action and diminishing the tendency of the ink'to flow from the reservoir through the feed element and to the writing element. Upon further writing, ink is drawn into the writing element from the space 4@ before any further ink will be drawn from the reservoir. When a sufficient quantity of the ink has been withdrawn from the space 4t the venting action again takes place and permits further ink to be withdrawn from the reservoir.

When the ink in the reservoir has been exhausted by writing the cartridge may be removed and replaced by merely unscrewing the rear end cap and withdrawing the cartridge, whereafter a fresh full cartridge may be inserted and the rear end cap replaced.

It will be seen from the foregoing that th present invention provides a writing instrument whichl is very simple in construction and which can be made very inexpensively, but which at the same time is effective in operation. The

writing point is of such form and so mounted that there are no highly critical dimensions or spacings which must be observed in order to provide satisfactory operation. It is important, of course,.that the pores in the feed element and writing element be of such size as to provide the desired passage of ink therethrough and the proper venting action. However, the dimensions of the foregoing elements and the positioning thereof in the'barrel are not very critical.

The writing element is of such form and so mounted that there is no likelihood of cloggingr of the ink flow passages by lint from the pocket of the user or fibers or sizing material from the paper with which the instrument is used in writmg.

The venting action insures an even flow of ink from the reservoir to the writing point, determined by the rate of withdrawal of ink from the writing point, and also insures against flooding such as might otherwise occur, as, for example, from the heating of the contents of the reservoir owing to the heat of the hand when the instrument is held in the hand in writing.

claim:

l. In a writing instrument of the type having a casing with a vent opening in its rearportion, and an ink vreservoir in said casing vented through said opening, the combination of `a hollow, shelllike writing element formed of porous sintered metal the pores of which provide interconnected capillary ink feed spaces, said element being stationarily mounted in the forward end of the casing, and deiining a chamber communicating with 'the atmosphere solely through said pores and through said reservoir, and ink feed means stationarily mounted in the forward end of said casing in constant engagement with the writing element, said ink feed means dening a first passage of substantially greater crosssectional area than said pores extending from the reservoirv to the interior of said writing element and a plurality of other passages of capillary size and of smaller size than said rst passage connecting the latter with the pores of said writing element, said other passages communicating with said rst passage throughout a substantial portion of the latter and with the pores of said writing element throughout a substantial area, said casing having a portion surrounding said writing element, except the writing tip thereof, and spaced from said element a distance providing a substantially uniform capillary space communicating forwardly with atmosphere for receiving and storing ink owing from the reservoir in excess of that required for writing.

2. A writing instrument comprising a casing having an open end, an ink reservoir in said casing vented to atmosphere, a hollow, shell-like Writing element formed of porous material the pores of which provide interconnected capillary ink feed passages, said Writing element being stationarily mounted in the casing and having a closed Writing tip projecting through the open end of said casing and dening an air chamber communicating with the atmosphere solely through the pores of said writing element and through said reservoir, the external walls of said writing element rearwardly of the tip being close to but spaced from the internal walls of said casing to dene a substantially uniform capillary space communicating forwardly with atmosphere adapted to receive and retain ink which flows from the reservoir in excess of that required for writing, and ink feed means stationarily mount- 'ged'in Said casing and constantly .connecting said reservoir in ink V)feg-Kling;-re1e tion with the pores `in seidV writing `eexnent at the portion thereof remote from said ftip. v Y

=3. l1-writing instrument oompr-ising e easing havingV an open end, e `reservoir Yin said Aeasing l vented to atmosphere, a hollow, shell-like writing Velem-Lent formed of porousrsintered v metal the poresjof which provide interconnected capillary ink yfeed specesLsaid writing element having a -cosed writing tip and being mounted in vseid casing Witnrsaid writing tip projecting through he ropening Vinthe casing and its lexternal Walls `reel*werdly of Seid 'tipspaced from but close Yto the interior walls of Seid casing to provide a.

feapillaryrspace vented through the'open end of Asaid and adapted to receive and retain which Hoi/vs from the reservoir excess of thatrequired Vfor writing, and an `ink feed element in easing formed of porous sintered metal the Apores of which provide interconnected References cited in the me of this patent UNITE-D STATES VPATENTS Number VName Date Re. 22,118 Lohrey June 16, 1942 535,588 Horton Mar. 12, 1895 1,426,200 Kovacs Aug. 15, 1922 2,107,150 Heising Fe 1, 1938 2,110,578 Prasch Mar. 3, 1938 Y 2,175,349 Hamer Oct. 10, 1939 2,195,430 Shea Apr. 2, 1940 2,252,907 Winter Aug. 19, 1941 2,330,053 l Herb Sept. 21, 1943 2,336,028 Nichol 'Dec. 7, 1943 2,375,770 'Dahlberg May 15, 1915 2,396,058 Rath Mar. 5, 1946 2,427,033 Wehl Sept. 9, 1947 2,431,015 Andrews et al Nov. 13, 19117 FOREIGN PATENTS vNumber Country Date Y627,713 Germany Feb.V 6, 1937 526,283 Greet Britam Sept. 13, 1940 

